Seating structure and methods for the use thereof

ABSTRACT

A seat with an adjustable seat depth is also provided, along with various methods for operating the different aspects and embodiments of the seating structure. In one embodiment, a seating structure includes a support structure and a carriage moveably supported by the support structure. The carriage is moveable relative to the support structure in opposite first and second longitudinal directions. A flexible body support member has a first portion coupled to the support structure, a second portion coupled to the carriage, and a third curved portion positioned between the first and second portions. The third portion is moveable toward and away from the support structure as the carriage is moved relative to the support structure in the first and second directions respectively.

This application is a continuation of U.S. application Ser. No.12/012,002, filed Jan. 28, 2008, now U.S. Pat. No. 7,922,248, whichclaims the benefit of U.S. Provisional Application No. 60/898,421, filedJan. 29, 2007, the entire disclosures of which are hereby incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates generally to seating structures, and inparticular, to a chair having unique kinematics, a body supporting seatand back, and an adjustable seat depth, and methods for using and/oradjusting the chair, including without limitation one or more of theseat and backrest.

BACKGROUND

Chairs of the type typically used in offices and the like are usuallyconfigured to allow tilting of the seat and backrest as a unit, or topermit tilting of the backrest relative to the seat. Typically, however,the seat and back are not individually adjustable, and are notindividually articulated during tilting. Such chairs therefore sometimescannot be easily adjusted or customized by the user to accommodate theparticular size, shape and/or desired posture of the user.

For example, the seat is typically formed as a relatively rigid, orfixed component, without any articulation between variousbody-supporting portions of the seat. As such, when a user tiltsrearwardly in the chair, the user may tend to slide forward in the seat,even when tilting rearwardly. At the same time, any adjustment of thedepth of the seat, measured from the front leading edge to the rearthereof, typically is provided by moving the entirety of the rigid,unitary seat in a fore-aft direction, which can lead to an unsightly gapforming at the rear of the seat and can also form a pinch point at thatlocation. Moreover, such chairs must provide for structure to allow theseat to move relative to the backrest while at the same time bearing theload of the seat and user. Moreover, such chairs typically must employan extra support member which allows the seat to move thereon, forexample, when the seat and/or support member are integrated into thelinkage assembly.

In typical tilt chairs, a static angular position of the chair backrelative to the seat is typically fixed when the chair is in an unloadedupright position, which may not be particularly well suited for a widerange of users. Moreover, the back is typically formed as a relativelyrigid, or fixed component, again without any articulation betweenvarious portions of the back. As such, the chair back does not allow theuser a full range of motion, precluding for example the ability of theuser to stretch or arch their back in a concave contour.

Tilt chairs normally employ compression and/or tension springs, torsionsprings and/or torsion bars, or leaf springs to bias the seat and backupwardly and to counterbalance the rearward tilting of the user. Themechanisms used to adjust the load on the spring(s), or the loadcapability of the spring(s), typically are complicated, and/or requiremultiple, excessive rotations of a knob or other grippable member toobtain the desired setting. Moreover, the chairs lack any indicia forthe user to determine the setting of the return force of the springbefore the user sits or applies a load to the backrest.

Moreover, such tilt chairs often do not provide a balanced ridethroughout the range of tilting motion of the chair. Specifically, therestoring force or torque of the chair, and in particular the spring,does not match the force or torque applied by the user throughout thetilting range. Although the applied force and restoring force maybalance out at a particular tilt position, such balance does nottypically occur throughout the tilting/recline range. Moreover, suchbalance typically cannot be achieved for a variety of users havingdifferent weights and body sizes. As such, the user must exert energyand/or apply an external force to maintain the chair in a particularlocation.

SUMMARY

The present inventions are defined by the claims, and nothing in thissection should be read as a limitation on those claims. Rather, by wayof general introduction and briefly stated, various preferredembodiments are described that relate to a tiltable chair having anarticulated seat and back, an adjustable seat depth, various controlmechanisms and linkage assemblies, and methods for the use of thevarious aspects.

For example and without limitation, in one aspect, the preferredembodiments relate to a seating structure having a seat with a forwardportion and a rear portion. The seat is tiltable between at least anupright tilt position and a reclined tilt position. The rear portion isautomatically pivotable relative to the forward portion as the seat istilted between the upright and reclined tilt positions.

In one embodiment, a back is coupled to the seat and is tiltable betweenat least an upright tilt position and a reclined tilt position. The backincludes a lower portion and an upper portion. The upper portion ispivotable relative to the lower portion between a neutral position andan extended position, with the upper portion being pivotable relative tothe lower portion independent of the tilt position of the back. In apreferred embodiment, the upper portion is pivotable relative to thelower portion when the rearward tilting, or tilt position, of the lowerportion is limited.

In another aspect, a seating structure includes a base component, afirst link member pivotally connected to the base component at a firsthorizontal pivot axis and a second link pivotally connected to the firstlink at a second horizontal pivot axis spaced from the first pivot axis.A portion of the second link extends in a longitudinal direction. Athird link is pivotally connected to the second link at a thirdhorizontal pivot axis spaced from the second pivot axis in thelongitudinal direction, and the third link is pivotally connected to thebase component at a fourth horizontal pivot axis spaced from the firstpivot axis. The third link also includes a portion extending in thelongitudinal direction.

A seat includes a front, thigh supporting region coupled to thelongitudinally extending portion of the second link and a rear buttocksupporting region coupled to the longitudinally extending portion of thethird link. The rear buttock supporting region is spaced rearwardly fromthe thigh supporting region in the longitudinal direction. The thirdlink is pivotable in a first direction relative to the second link aboutthe third pivot axis between an upright position and a reclinedposition. An upper surface of the rear region of the seat forms an angleof greater than 180 degrees relative to an upper surface of the frontregion when the third link is in the reclined position.

In a preferred embodiment, a backrest has a lower portion non-pivotallycoupled to one or both of the rear region of the seat and the thirdlink. In one embodiment, the backrest includes an upper portion coupledto a back support member, with the back support member being pivotallyconnected to the base component about a fifth horizontal pivot axis,which is coincidental with the fourth pivot axis in one embodiment.

In yet another aspect, a seating structure includes a base component anda back support member having a lower support member pivotally connectedto the base component about a first horizontal pivot axis and an uppersupport member pivotally connected to the lower support member about asecond horizontal pivot axis spaced from the first pivot axis. At leastone backrest component is coupled to the upper support member. Anadjustment mechanism is coupled between the lower support member and theupper support member. The adjustment mechanism is operable between atleast first and second positions. The upper support member is pivotablerelative to the lower support member about a horizontal axis between atleast first and second support positions as the adjustment mechanism isoperable between the at least first and second positions.

In another aspect, a seating structure includes a base component and abody support member pivotally coupled to the base component. A springbiases the body support member toward an upright position. Aforce-adjusting member engages the spring and is moveable between atleast first and second force applying positions. An actuator is coupledto the force-adjusting member and includes a grippable member that istranslatably moveable relative to the base component between at leastfirst and second adjustment positions. The force-adjusting member ismoved between the first and second force applying positions as thegrippable member is moved between the first and second adjustmentpositions.

In one embodiment, the spring is configured as a leaf spring and theforce-adjusting member is configured as a fulcrum member. The fulcrummember is moveable in a fore-aft direction along a longitudinal axisbetween at least first and second fulcrum positions, with the actuator,and in particular the grippable member, moveable therewith in thefore-aft direction.

In yet another aspect, a seating structure includes a base componenthaving a support surface and a fulcrum member moveable in opposite firstand second longitudinal directions. The fulcrum includes a first rollerrotatably supported by the support surface of the base component and asecond roller contacting the first roller. The first roller is rotatablein first and second rotational directions as the fulcrum member is movedin first and second longitudinal directions respectively, while thesecond roller is rotatable in first and second rotational directions asthe fulcrum member is moved in the second and first longitudinaldirections respectively. In essence, the first and second rollers rotatein the opposite directions as the fulcrum is moved longitudinally. Inone embodiment, at least one leaf spring is supported by the secondroller.

In yet another aspect, a seating structure includes a leaf spring and abody support structure biased by the leaf spring. One of the leaf springand the body support structure has a cam with a convex cam surface,while the other of the leaf spring and the body support structure has acam follower with a concave cam surface. In operation, the cam followerengages the cam with the cam surfaces contacting one another.

In yet another aspect, a seating structure includes a support structureand a carrier moveably supported by the support structure. The carrieris moveable relative to the seat support structure in opposite first andsecond longitudinal directions. A flexible body support member includesa first portion fixedly coupled to the seat support structure, a secondportion coupled to the carrier, and a third curved portion positionedbetween the first and second portions. The third portion is moveabletoward and away from the support structure as the carrier is movedrelative to the seat support structure in the first and seconddirections respectively. In one preferred embodiment, a cover member isdisposed over an outer surface of the body support member and covers thethird portion of the body support member.

The various aspects and embodiments provide significant advantages overother tilt chairs and seating structures, including chairs and seatingstructures having backrests, seats and tilt controls. For example, inone preferred embodiment, a rear portion of the seat automaticallypivots rearwardly relative to a front portion, with the rear and frontportions opening up and forming an angle greater than 180 degreesrelative to each other, as the user tilts rearwardly in the chair. Inthis way, the rear portion provides support for the ischial tuberositiesor buttock region of the user and prevents the user from slidingforwardly on the front portion of the seat. By separating the ischialtuberosities or buttock support region from the thigh support region,the entirety of the seat support surface does not have to tipped orpivoted as the user tilts rearwardly. As a result, the hip drop (theamount the hip joint of the user drops during recline) is reduced,thereby providing for tighter package space between the seat surface andtilt control, less energy stored in the tilt (as required to lift theuser back up), and lower torques at the given angular travel.

In addition, the static angle of the back in an upright, neutralposition can be easily and quickly adjusted relative to the seat so asto allow the user to customize the fit of the chair for their particularbody size and shape. In addition, in one embodiment, the upper portionof the back can be independently pivoted relative to the lower portionof the back, for example when the user arches their back or extendstheir arms and shoulders rearwardly, while simultaneously supporting theuser's back in the arched position. The upper portion will returnautomatically to a neutral position when the biasing force of the useris relieved.

The biasing mechanism also provides advantages. For example and withoutlimitation, the actuator, and in particular the grippable portion, foradjusting the return force of the spring is translatable relative to thebase component. By viewing the position of the grippable portion, or anyother visible portion of the actuator, the user is provided with visualindicia as to the setting of the return force before they sit downand/or apply a force against the backrest.

In addition, when a leaf spring and adjustable fulcrum are used to applythe return biasing force to the seating structure, the first and secondrollers used to support the spring on the base component allow for easy,relatively frictionless movement of the rollers relative to the basecomponent and spring. As such, the position of the fulcrum can be easilyadjusted even when the leaf spring is loaded.

The cam surfaces formed on the spring and the body support structurealso provide advantages. In particular, the cam surfaces provide abalanced ride to all types of various users throughout the normaltilting range of the seating structure. In essence, this providestailored torque outputs as disclosed for example and without limitationin U.S. application Ser. No. 10/738,641, filed Dec. 17, 2003 andentitled “Tilt Chair and Methods for the Use Thereof,” the entiredisclosure of which is hereby incorporated herein by reference. The camsurfaces eliminate the need for a spring link as disclosed in U.S.application Ser. No. 10/738,641, filed Dec. 17, 2003.

The embodiments of the adjustable seat also provide advantages. Forexample, the depth of the seat can be adjusted without having to movethe entire seat, or in other words, while maintaining a rear portion ofthe seat in the same position. Such construction avoids the need foradditional support members. In addition, the adjustment mechanism can beeasily grasped and manipulated by the user to adjust the depth of theseat. Moreover the curved front portion of the seat providestransitional support for the user's legs when sitting down or standingup from the chair. At the same time, the curved portion is relativelyflexible, thereby avoiding pressure points along the thighs of the user.

Of course, it should be understood that the various aspects disclosedherein can be used individually or in combination, with variouscombinations providing additional advantages. The present invention,together with further objects and advantages, will be best understood byreference to the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a chair.

FIG. 2 is a schematic side view of a chair in an upright position.

FIG. 3A is a schematic side view of the linkage assembly for the chairshown in FIG. 2.

FIG. 3B is a schematic side view of the linkage assembly for the chairshown in FIG. 2 in an intermediate reclined position.

FIG. 3C is a schematic side view of the linkage assembly for the chairshown in FIG. 2 when in a fully reclined position with an upper backsupport member in a neutral position.

FIG. 3D is a schematic side view of the linkage assembly for the chairshown in FIG. 2 when in a fully reclined position with the upper backsupport member in an extended position.

FIG. 4A is an enlarged, partial side view of the back support member ina neutral position.

FIG. 4B is an enlarged, partial side view of the back support member inan extended position.

FIG. 5 is an exploded perspective view of a tilt control mechanism.

FIG. 6 is an exploded perspective view of various components of thelinkage assembly.

FIG. 7 is a bottom exploded perspective view of the seat supportincluding an adjustable seat depth mechanism.

FIG. 8 is a top exploded perspective view of the seat support and seatdepth mechanism shown in FIG. 7.

FIG. 9 is an exploded perspective view of a fulcrum assembly.

FIG. 10 is a perspective view of a tilt control mechanism.

FIG. 11 is a cut-away perspective view of a back support member and leafspring.

FIG. 12 is a front partial perspective view of the seat and tilt controlmechanism.

FIG. 13 is a perspective view of a seat member.

FIG. 14 is a top partial perspective view of the seat.

FIG. 15 is a bottom partial perspective view of the seat.

FIG. 16 is a side cut-away view of the seat.

FIG. 17 is a top perspective view of a seat cover.

FIG. 17A is a cross-sectional view of the seat cover engaging the seatframe.

FIG. 18 is a side cut-away view of the seat, tilt control mechanism andback support member in an upright position.

FIG. 19 is a side cut-away view of the seat, tilt control mechanism andback support member in a reclined position, with the back support memberin a neutral position.

FIG. 20 is a side cut-away view of the seat, tilt control mechanism andback support member in a reclined position, with the back support memberin an extended position.

FIG. 21 is a partial, side cut-away view of the back support member in aforward position.

FIG. 22 is a partial, side cut-away view of the back support member inan intermediate, nominal position.

FIG. 23 is a partial, side cut-away view of the back support member in arearward position.

FIG. 24 is a front perspective view of the back support member.

FIG. 25 is a rear perspective view of the back support member.

FIG. 26 is a partial perspective view of a lower portion of the upperportion of the back support member.

FIG. 27 is an exploded view of a back angle adjuster.

FIG. 28 is a side view of a back support member bracket.

FIG. 29 is a perspective view of a lower wedge component.

FIG. 30 is a side view of the lower wedge component shown in FIG. 29.

FIG. 31 is a perspective view of an upper wedge component.

FIG. 32 is a perspective view of a first portion of a wedge actuator.

FIG. 33 is a side view of a second portion of a wedge actuator.

FIG. 34 is a front perspective view of a back suspension structure.

FIG. 35 is front view of a pad structure.

FIG. 35A is an enlarged view of a connector between pads.

FIG. 36 is an enlarged partial perspective view of a back suspensionstructure.

FIG. 37 is a front view of a cover carrier member.

FIG. 38 is a side view of the carrier member shown in FIG. 37.

FIG. 39 is a side view of the chair.

FIG. 40 is a cross-sectional view of an actuator assembly.

FIG. 41 is an enlarged view of the end of the actuator assembly shown inFIG. 40 taken along detail 41.

FIG. 42 is an exploded perspective view of another embodiment of a tiltcontrol mechanism.

FIG. 43 is a cut-away perspective view of a back support member and leafspring.

FIG. 44 is a partial exploded perspective view of the tilt controlmechanism shown in FIG. 42.

FIG. 45 is an exploded perspective view of another embodiment of a backangle adjustment mechanism.

FIG. 46 is a front, perspective view of another embodiment of a backsupport member.

FIG. 47 is a front perspective view of the chair without the fabriccover.

FIG. 48 is a side view of the chair without the fabric cover in arearward, neutral, upright position.

FIG. 49 is a side view of the chair without the fabric cover in anominal, neutral, upright position.

FIG. 50 is a side view of the chair without the fabric cover in aforward, neutral, upright position.

FIG. 51 is a side view of the chair without the fabric cover in anominal, upright position, with the upper portion in an extendedposition.

FIG. 52 is a side view of the chair without the fabric cover in anominal, neutral, intermediate recline position.

FIG. 53 is a side view of the chair without the fabric cover in anominal, neutral, full recline position.

FIG. 54 is a side view of the chair without the fabric cover in anominal, full recline position, with the upper portion in an extendedposition.

FIGS. 55A and B are partial cross-sectional views of a fabric attachmentassembly.

FIG. 56 is a partial, perspective view of the seat.

FIG. 57 is a partial, exploded perspective view of a portion of the seatassembly.

FIG. 58 is a partial, perspective view of the seat.

FIG. 59 is an exploded view of the seat shown in FIG. 58.

FIG. 60 is an exploded view of various components of the linkageassembly.

FIG. 61 is a perspective view of the chair.

FIG. 62 is a perspective view of the chair without a pad structure orouter cover.

FIG. 63 is a rear view of the chair shown in FIG. 62.

FIG. 64 is a front view of the chair shown in FIG. 62 with the padstructure.

FIG. 65 is an exploded perspective view of a flexible body supportmember and a load support layer of a suspended pixilated seat structure.

FIG. 66 is a bottom, front perspective view of the fulcrum assembly.

FIG. 67 is a rear perspective view of the back frame.

FIG. 68 is portion of an alternative embodiment of a pad structure.

FIG. 69 is portion of an alternative embodiment of a pad structure.

FIG. 70 is portion of an alternative embodiment of a pad structure.

FIG. 71 is an enlarged cross-sectional view of one embodiment of aconnection between a pad structure and a backrest frame.

FIG. 72 is an enlarged cross-sectional view of an alternative embodimentof a connection between a pad structure and a backrest frame.

FIG. 73 is an enlarged cross-sectional view of an alternative embodimentof a connection between a pad structure and a backrest frame.

FIG. 74 is an enlarged cross-sectional view of an alternative embodimentof a connection between a pad structure and a backrest frame.

FIG. 75 is an enlarged cross-sectional view of an alternative embodimentof a connection between a pad structure and a backrest frame.

FIG. 76 is an enlarged cross-sectional view of an alternative embodimentof a connection between a pad structure and a backrest frame.

FIG. 77 is a side view of an alternative embodiment of a chair with aforward tilt shown in a forward tilt position.

FIG. 78 is a side view of the chair shown in FIG. 77 with the chair in aneutral position.

FIG. 79 is an exploded view of a fabric attachment assembly for a seat.

FIG. 80 is an exploded view of a fabric attachment assembly for abackrest.

FIG. 81 is a side view of a cover and handle assembly.

FIG. 82 is an opposite side view of the cover and handle assembly shownin FIG. 81.

FIG. 83 is a perspective view of the handle shown in FIG. 81.

FIG. 84 is a perspective view of the cover shown in FIG. 81.

FIG. 85 is a partial perspective view of various seat depth components.

FIG. 86 is a cross-sectional view of the assembly shown in FIG. 85.

FIG. 87 is a partial perspective view of the upper backrest assembly.

FIG. 88 is a cross-sectional view of the backrest shown in FIG. 87 takenalong line 88-88.

FIG. 89 is a side view of one embodiment of an upper backrest assembly.

FIG. 90 is a side view of one embodiment of the chair.

FIG. 91 is a back review of the chair shown in FIG. 90.

FIG. 92 is a partial cut away view of a portion of a backrest assembly.

FIG. 93 is an enlarged portion of FIG. 92 taken along line 92.

FIG. 94 is a cross-sectional view of the connector assembly shown inFIGS. 92 and 93 taken along a direction substantially perpendicular tothe cut away of FIG. 92.

FIG. 95 is an alternative embodiment of the pad structure.

FIG. 96 is a rear perspective view of one embodiment of a backreststructure.

FIG. 97 is an enlarged view of the backrest structure shown in FIG. 96and taken along line 97.

FIG. 98 is a partial perspective view of a link with a snap-fit rotationdevice.

FIG. 99 is a cross-sectional view of the link shown in FIG. 98 securedto a frame member.

FIG. 100 is a side view of a cover attached to the chair.

FIG. 101 is a cross-sectional view of the cover and frame taken alongline 101-101 of FIG. 100.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

General:

The terms “longitudinal” and “lateral” as used herein are intended toindicate the directions 50, 52 of the chair from front to back and fromside to side, respectively. Similarly, the terms “front”, “side”,“back”, “forwardly”, “rearwardly”, “upwardly” and “downwardly” as usedherein are intended to indicate the various directions and portions ofthe chair as normally understood when viewed from the perspective of auser sitting in the chair. It should be understood that the terms“mounted,” “connected”, “coupled,” “supported by,” and variationsthereof, refer to two or more members or components that are joined,engaged or abutted, whether directly or indirectly, for example, by wayof another component or member, and further that the two or moremembers, or intervening member(s) can be joined by being integrallyformed, or by way of various fastening devices, including for exampleand without limitation, mechanical fasteners, adhesives, welding, pressfit, bent-over tab members, etc. The term “plurality” means two or more.

Linkage Assembly:

Referring to the drawings, FIGS. 1-6, 18-20, 42, 48-54 and 58-60 show apreferred embodiment of the chair having tilt control housing 2, seat 4,back support member 8 and back 6. It should be understood that the term“housing” generally refers to any support member that supports anothermember, and includes, but is not limited to a structure that provides anenclosure. The seat 4 and a lower portion 12 of the back are supportedby a linkage assembly 10, which is pivotally connected to the tiltcontrol housing 2. The tilt control housing 2 forms a base component ofthe linkage assembly. The tilt control housing is formed by an upperbracket 14 and lower bracket 16, which are joined, for example bywelding.

The linkage assembly 10 includes a first link 18, 518 having a first endpivotally connected to a pair lugs 20, extending forwardly from a frontportion of the tilt control housing or base component, at a firsthorizontal pivot axis 22. The first link 18, 518, or front link, can beformed from any suitable material, including metal or a plastic, such asa 30-33% GF nylon. The first link extends upwardly and has a second endpivotally connected to a front seat frame 24, 524, which forms a secondlink, at a second horizontal pivot axis 26 formed on a downwardlyextending U-shaped support or leg 28, 528. Preferably, only a singlefirst link is provided, and is secured to the middle of the support 28,528. As shown in FIGS. 47 and 59, the upstanding portions of the support528 are curved in two planes and extend upwardly and rearwardly from thepivot axis 26. Alternatively, a pair of first links can be providedalong opposite sides of the seat. A pivot axle 32 can be integrallyformed on one or the other, or both, of the first and second links 18,518, 24, 524. Alternatively, a separately formed axle can be used tosecure the first and second links. In one embodiment, the axle 32 isformed on the first link, which includes a plurality of round ribs thatride along a bushing 30 secured between the first and second links. Theend portions of the axle 32 snap into the second link, while the roundribs carry the load. A socket or recess 36 is formed in the second linkto receive the axle, bushing and ribs. A cover member 38 is disposed andconnected over a forwardly facing portion of the seat frame to providean aesthetically pleasing appearance. The seat frame is preferably madeof glass filled nylon, although it should be understood that it can bemade form a variety of materials, including metal, plastic, composites,and combinations thereof.

In another embodiment, shown in FIGS. 98 and 99, a front link 1018includes a pair of axles or posts 1020 extending laterally outwardlyfrom opposite sides of the front link. A pair of bushings 1026 areaxially disposed on the posts, and include an inwardly extendingresilient arm 1028 with an enlarged end portion defining a catch member1030. A seat frame 1040 includes a laterally extending recess 1042shaped to rotatably receive the pivot member and attached bushings. Theframe 1040 includes a pair of spaced apart radially extending catchmembers 1032. The catch members 1032 are positioned such that oppositeouter walls 1046 thereof are substantially aligned with the outer catchportions 1030 of the resilient arms when the link and frame are engaged,so as to prevent relative axial movement between the link and frame andwith the engagement between the posts and socket preventing relativeradial movement between the link and frame, thereby rotatably securingthe link to the frame. The end of the recess is formed as a socket 1024shaped to rotatably receive the bushings 1020. The overall length of therecess 1042, or the individual depth of each socket 1024 on each sidethereof, are greater than the overall length of the link (from one postend to the other), or greater than the individual length of the axle andhub, with a gap 1022 formed between the edge of the link and mouth ofthe frame on each side of the link.

In operation, an assembler slides one end (e.g. left side) of thebushing/axle 1020, 1026 all of the way into a corresponding socket 1024such that the gap 1022 on that side is eliminated and such that anopposite bushing/axle 1020, 1026 clears the mouth of the recess on theother side (e.g., right side) and is aligned along a pivot axis 1034. Atthis initial insertion stage, an opposite catch member 1030 (e.g., rightside) is biased radially outwardly by a corresponding catch member 1032(e.g., right side) on the frame. The user then moves the link 1018 in anaxial direction along axis 1034 toward the opposite end until the biasedcatch member 1030 (right side) slides past the catch member 1032 on theframe and snaps into place, thereby rotatably securing the link to theframe. As shown, the link can be installed from either side, and istherefore not left or right handed. It should be understood, however,that the mechanism could be configured with a single catch member on thelink and a single catch member on the frame, with an opposite elongatedsocket in the frame to initially receive the link axle. It should beunderstood that this device can be used to rotatably secure any twocomponents, and is not limited to the frame and link for a chair asshown and described. It should also be understood that the resilient armand/or bushing can be integrally formed with the link component. Inaddition, the arm and catch portions can be used to secure any twocomponents in a non-rotatable engagement, for example where theconfiguration of the socket or end post, or other non-rotation members,are configured to prevent such rotation. The device provides for twocomponents to be non-axially and non-radially moveable relative to eachother without having to provide an opening or access for a pin to beinserted along the rotation axis.

Referring to FIGS. 6-8 and 57-60, the front seat frame 24, 524, orsecond link, has a pair of substantially horizontal arms 40, 540 thatare spaced apart in the lateral direction and form an opening 42therebetween. The arms 40 extend rearwardly in the longitudinaldirection 50 from the front to the rear of the chair. Each arm isconfigured with a guide 44, 544 or track that opens to the front of theframe. Each arm preferably has an L-shaped cross section defining asubstantially horizontal flange 46, 546 and a vertically oriented flange48, 548. A plurality of fingers 54, 554 extend upwardly from a top ofthe vertical flange and are adapted to anchor a fabric 56 by way of acarrier member, shown in FIG. 17, which snaps onto the frame. Forexample, the fingers can be configured with barbs or catch members atthe ends thereof for engagement with a carrier or other cover component.In other embodiments, the seat frame is formed with a female receptaclethat receive a male portion formed on the carrier member. Varioussuitable embodiments for forming the fabric and carrier, and securingthem to a support structure, are disclosed in U.S. application Ser. No.10/796,406, filed Mar. 8, 2004 and entitled “Fabric Attachment Device,”the entire disclosure of which is hereby incorporated herein byreference. In the embodiment shown in FIGS. 59 and 60, the flange 548 isnot linear, but rather has a slight concave profile, and then tapers orslopes downwardly toward the horizontal flange 546 toward the rearportion of the second link 524.

In an alternative embodiment, the carrier member is omitted. Instead,the fabric is provided with a plurality of fastener components, such asChristmas tree fastener or snap-fit fastener, that engage openings inthe frames with a snap fit. The fabric can also be secured with othermechanical fasteners, by bonding, or by various combinations thereof.For example, as shown in FIG. 79, a frame member 221 is attached to anedge portion 225 of the cover, e.g., fabric or textile material, with astaple, bond, sewing etc., or combinations thereof. A Christmas treefastener 223 is then secured through the frame member 221 and into theseat frame, with the cover wrapping around the inner frame and coveringthe head of the fastener 223.

Referring to FIG. 80, a frame member 321 is again secured to an edgeportion of the cover with bonding, stapling, sewing etc., orcombinations thereof. The frame has a U-shaped socket in which aretainer clip 327, e.g., tinnerman clip, is inserted. The clip 327releasably engages a forwardly facing flange portion of the backrestframe 302, with the fabric wrapping around the edge of the frame member321 and then across the front of the pad structure.

Referring to FIGS. 6-8 and 57-60, a plurality of engagement/support arms58, 558 extend upwardly from an inboard edge of each horizontal flange46, 546. The support platforms are each configured with an enlarged headportion 60, 560. The engagement/support platforms are joined to asuspended body support member, which defines a portion of the seat. Inparticular, a front, thigh-supporting region 62 of the seat is coupledto the arms of the front seat frame.

For example, a membrane can be disposed across the opening and beengaged with the support platforms or fingers on each arm, as shown forexample in U.S. application Ser. No. 10/738,641, filed Dec. 17, 2003,published as U.S. Publication No. 2004/0183350 A1 and entitled “TiltChair and Methods for the Use Thereof,” the entire disclosure of whichis hereby incorporated herein by reference. In one alternativeembodiment, the suspended body support member is configured as asuspended pixelated seat structure, as shown for example and withoutlimitation in U.S. Application Ser. No. 11/433,891, filed May 12, 2006and entitled “SUSPENDED PIXELATED SEATING STRUCTURE”, the entiredisclosure of which is hereby incorporated herein by reference. Inparticular, as shown in FIGS. 12-17, the suspended pixilated seatstructure has a frame component 64 having plurality of openings throughwhich the support arms are disposed, with the enlarged heads engagingthe frame with a snap-fit. The suspended pixilated seat structurefurther includes a macro compliance layer 66, including for example aplurality of primary support rails, joined to the frame, a microcompliance layer 68, including for example a plurality of springelements, joined to the macro compliance layer, and a load support layer70, including a plurality of pixels connected to the springs.

In one embodiment, shown in FIGS. 56 and 59, the macro compliance layer66 is connected directly to the frame. In particular, each strip 67 ofthe macro layer has a T-shaped head portion 69, which is disposed in theopening between two adjacent support arms 558. The enlarged head 560extends over the T-shaped head portion and holds the strip to the frame.The head 69 also has an opening therethrough which receives one of theposts 71 positioned between adjacent arms 558.

Referring again to FIGS. 6-8 and 57-60, a rear seat frame 72, 572, whichforms a third link, has a pair of arms 74, 574 extending forwardly inthe longitudinal direction 50. The arms are spaced apart in the lateraldirection 52 and are substantially aligned with the arms 40, 540 of theforward seat frame, with the free ends of the arms 40, 540, 74, 574substantially abutting. The arms 74, 574 are configured similar to thearms of the front seat frame, and include horizontal and verticalflanges 76, 576, 78, 578 upwardly extending fingers 80, 580 and upwardlyextending engagement/support members 82, 582 and posts 71 which areconfigured to support a suspended body support member as just explained.In particular, a rear, buttock-supporting region 84 of the seat iscoupled to the arms of the rear seat frame, where the buttock-supportingregion 84 is spaced longitudinally rearwardly from the thigh-supportingregion 62. In the embodiment shown in FIGS. 59 and 60, the flange 578 isnot linear, but rather has a slight concave profile, and then tapers orslopes downwardly toward the horizontal flange 576 toward the frontportion of the third link 524. The flanges 548 and 578 in combinationform a V-shaped opening when viewed from the side. The opening helpsprevent the carrier member or other component of the fabric, fromexperiencing excessive tension as the rear seat frame 572 pivotsrelative to the front seat frame 524.

A pair of leaf springs 86, 586 bridge or span the gap between the freeends of the arms 40, 540, 74, 574 of the front and rear seat frames andare secured, for example with adhesive and/or fasteners 587, to thehorizontal flanges 46, 546, 76, 576 of each of the arms. A plurality ofposts 589 further support the macro compliance layer 66. The leafsprings 86 pivotally connect the front and rear seat frames, or secondand third links, at a virtual horizontal pivot axis 88. In analternative embodiment, the second and third links can be pivotallyconnected at a hard pivot axis, for example with a pivot member. Itshould be understood that the pivot axis can be defined as a compliantjoint allowing two components to pivot relative to each other, and thatthe position of the axis (actual or virtual) may change or move over therange of pivoting between the two components.

The rear seat frame has a pair of downwardly extending support members90, 590, positioned along each side of the frame. A pair of armrests 92are connected to and extend upwardly from the support members. The rearseat frame can be made from two parts, each of which can be a differentmaterial, for example glass-filled nylon and aluminum.

The rear seat frame 72, 572, or third link, also includes a pair offorwardly extending lugs 94, 594 that are pivotally connected to thetilt control housing 2, or base component, at a fourth horizontal pivotaxis 96. In this way, the base component 2, or tilt control housing,front pivot link 18, 518 and front and rear seat frames 24, 524, 72, 572define the four links of a four-bar linkage.

In operation, and as best shown in FIGS. 3A-3D and 48-54, the user tiltsrearwardly in the chair, and in particular the seat, from an uprightposition (FIGS. 3A and 48-51) through an intermediate recline position(FIGS. 3B and 52) to a fully reclined position (FIGS. 3C and 53). As theuser tilts rearwardly, the first link 18, 518 is pivotable relative tothe base component, or tilt control housing, about the axis 22 in afirst rotational direction (clockwise when viewed from the left-handside). At the same time, the third link 72, 572 or rear seat frame,pivots in the first rotational direction relative to the second link 24,524 or front seat frame about the pivot axis 88, such that the anglebetween the upper surface 96 of the front region 62 of the seat and theupper surface 98 of rear region 84 of the seat opens up as the usertilts rearwardly, and forms an angle of greater than 180° when the seatis in the reclined position, and preferably in any reclined positionrearwardly of the upright position. Indeed, in the initial uprightposition, the upper surface of the front region and the upper surface ofthe rear region forms a slight crown, with an angle greater than 180°,and desirably about 183°. In one embodiment, the rear seat region 84pivots rearwardly 18° relative to ground as the seat moves from theupright position to the fully reclined position, while the front seatregion 62 pivots only 3° relative to ground, such that the rear regionpivots 15° further than the front region, and forms an angle greaterthan 180°. In various embodiments, the angle between the upper surfaceof the front region and the upper surface of the rear region in thefully reclined position can vary between about 185° and 200°, andpreferably is about 195°. In this way, the rear region 84 of the seatprovides support for the ischial tuberosities or buttock region of theuser, and prevents the user from sliding forwardly in the seat as theuser tilts rearwardly in the chair. At the same time, the front region62 of the seat is maintained in substantially the same orientation (3°pivot) throughout the tilt range of the chair. By separating the rear,ischial support region from the front, thigh support region, theentirety of the seat support surface does not have to be tipped orpivoted as the user tilts rearwardly. As a result, the hip drop isreduced, thereby providing for tighter package space between the seatsurface and tilt control, less energy stored in the tilt, and lowertorques at the given angular travel.

Preferably, the first pivot axis 20 formed between the first link 18,518 and the tilt control housing 2 is positioned forwardly of the fourthpivot axis 96 formed between the third link 72, 572 and the tilt controlhousing 2, with the fourth pivot axis 96 positioned forwardly of thethird pivot axis 88 formed between the forward and rearward seat framesin one embodiment (FIGS. 2-3C), such that the third link 72, andconnected back support member 100 tilt rearwardly at a greater rate andangle than does the second link. In another embodiment, the fourth pivotaxis 96 and the third pivot axis 88 are substantially aligned vertically(FIGS. 48-54). The pivot axis 88 is aligned with the pivot axis 96, ordisposed rearwardly therefrom, so as to prevent the sensation ofpressure or lift mid-thigh on the user.

Referring to FIGS. 77 and 78, an alternative embodiment of the chair isconfigured with a linkage that allows for a forward tilt of the seat andbackrest. In particular, first link 421 his reposition with a first endportion pivotally connected to the second link 524 at the pivot axis 26,and a second end pivotally connected to the tilt housing at an axis 423.As the user tilts forwardly, the first link 423 is pivotable relative tothe base component, or tilt control housing, about the axis 423 in afirst rotational direction (counter-clockwise when viewed from theleft-hand side). At the same time, the second link 524 pivots relativeto the third link 572 such that the angle between the upper surface 96of the front region 62 of the seat and the upper surface 98 of rearregion 84 of the seat opens up as the user tilts forwardly, and forms anangle of greater than 180° when the seat is in the forward tiltposition. Indeed, in one embodiment, the angle between the upper surface96 and the upper surface 98 is always maintained at an angle greaterthan 180°, whether in a forward tilt position, an upright tilt positionor a reclined tilt position, with the angle between the rear uppersurface and the forward upper surface opening up even more as the userreclines, or tilts forwardly.

Additional Base Components:

An adjustable support column 102, preferably pneumatic and shown inFIGS. 1-3D, 5 and 48-54, is mounted to a rear portion of the housing 2at opening 104. A top portion of the column 102, having a side-actuatedlever (not shown), extends into the housing. A cable 106 is connected tothe lever, and can be moved within a guide to actuate the lever. Anopposite end of the cable is engaged by an arm portion 114 of the leverarm 108 pivotally connected to a fulcrum assembly, as shown in FIGS. 5and 9. The lever is actuated by a push button 110 extending from the endof a grippable handle 290 connected to an actuator tube. In operation,the user pushes the button 110, which laterally moves a rod that engagesan arm 112 and rotates the lever arm 108 about a vertical axis 288. Asthe lever 108 rotates, the arm portion 114 moves the cable 106 toactuate the support column lever, which in turn allows the supportcolumn 102 to extend in response to a gas spring contained therein, orto collapse in response to the weight of the user being applied to theseat. One suitable support column is available from Samhongsa Co. Ltd.,otherwise referred to as SHS.

In an alternative embodiment, shown in FIGS. 40 and 41, the actuator isconfigured as a joy-stick 600 rather than a push button. The joy stickincludes an arm or post portion 602 and a base 604 having acircumferential shoulder 606 that engages an annular support 608 formedon a spring retainer 610. The joy stick 600 is pivotable about any axislying within a plane 612 defined by the shoulder, i.e., a planesubstantially perpendicular to the longitudinal axis 614 the arm of thejoy-stick. The joy stick is moveable from an upright position, shown inFIG. 40, to an actuated position, with a spring 616 biasing thejoy-stick actuator toward the upright position.

The spring retainer 610 includes an internal cavity 618 having an endwall 620 engaging the spring 616. A cable 622 includes an enlarged endportion 624 connected to the base of the joy stick, preferably bydisposing the end portion in a cavity 626 having a narrow throat 628 anda frusto-conical shaped entryway 630. An enlarged spring engagingportion 632 is spaced from the end portion 624 along the length of thecable. In operation, the user grips or pushes on the end of the arm 602of the joy stick, which pivots about an axis defined by the junctionbetween the shoulder 606 and the annular support 608 of the springretainer. The spring 616 is compressed between the end wall 620 of thespring retainer and the enlarged portion 632 of the cable, which urgesthe joy stick back to an upright, or centered position when released bythe user. As the user pivots the joy stick 600, the cable 622 is movedrelative to a cable guide 634 from a first position to second positionand actuates the support column lever, which allows the support columnto extend or collapse. The joy stick 600 can be pivoted in any directionabout any point along the circumferential shoulder so as to actuate thesupport column. It should be understood that the joy-stick can be usedto actuate other components, and convert a pivoting/rotating movementinto a linear actuation, or back to a rotating/pivoting action at thedistal end of the cable. A grippable housing 690 surrounds and supportsthe spring retainer and joy stick. A bezel 636 is secured to the end ofthe housing, and is open along the axis such that the arm 602 extendsoutwardly for access by the user.

Referring to FIG. 1, a base 116, preferably a five arm base withcasters, is mounted to the bottom of the support column 102 in aconventional manner, although one of skill in the art would understandthat other support columns and bases can be used to support the housing,including fixed height support columns and non-rolling bases, includingfor example a base configured with glides.

With the chair being generally described, the various features of thearmrests, the seat, the backrest and the tilt control assembly, alongwith various controls therefore, will be described in more detail below.

Adjustable Seat Depth:

Referring to FIGS. 7-8, 12-17 and 56-69, the length of the front region62 of the seat (fore-aft longitudinal measurement) can be adjusted toalter the overall depth (front to back length) of the seat. The seatdepth assembly includes a rigid carriage member 118, 718 having alaterally extending support 120, 720 with a leading edge 122, 722. Inone embodiment, the leading edge is configured with a plurality of steps124 as shown in FIGS. 7-8 and 12-17. In the embodiment of FIGS. 56-59,the leading edge is linear, or extends forwardly with a generally convexcurvature. In the first embodiment, a center step portion 126 of theleading edge, formed along the lateral centerline of the carriage,extends forwardly, with a plurality of steps 128 (shown as two on eachside) disposed progressively rearwardly relative to the center step 126.At the outer lateral edges, one or more steps 130 progressively moveforward relative to the rearwardmost step. The carriage is provided witha pair of grippable handles 132, shown as tabs, which extend laterallyoutwardly and/or upwardly from each side of the seat. The carriage 118further includes a pair of rearwardly extending slide members 134 thatare slidably engaged with the guide/track 44 formed on each of the armsof the front seat frame. The carriage 118 is translatably moveablerelative to the front seat frame 24 in the longitudinal direction 50(fore-aft). The terms “translate,” “translatable” and variationsthereof, means to move or displace along a path (linear or non-linear(e.g., curved or curvilinear)) from one point to another point spacedapart by some distance. It should be understood that a component that istranslated relative to another component can also be rotated relative tothat same component, with the translation and rotation occurringsimultaneously, successively and/or both simultaneously andsuccessively. In one embodiment, a bushing 136 is secured to the seatframe in the guide 44 for engagement with the slide members.

In the embodiment of FIGS. 57-59, the carriage member 718 includes apair of opposite circular end flanges each having an opening disposedtherethrough. A vertical flange extends inwardly from the forwardportion of the end flange and is secured to a track or slide member 734.The slide members are slideable or translatable relative to aguide/track 744, which is secured to the first link or seat frame 524. Apair of end covers 745 each include flexible engagement members thatengage the opening in the end flanges of the carriage member. The coversare provided with an opening in which the user can insert a finger orthumb into for gripping and moving the carriage member. A fabric carrier747 wraps around and is moveable relative to a hub portion 749 formed onthe cover. The carrier member includes a pair of tethers 751 thatfurther wrap around a bearing portion 761 on the cover 745. The bearingportion is preferably curved and oriented with a curve about a verticalaxis. In this way, the carrier can be rotated about a horizontal axisand then a vertical axis formed by the bearing portion. This ability toslide past surfaces oriented in different planes or about different axesis facilitated by the user of a tether. The end of the tether 751 isformed with a plurality of enlarged portions or stops 763. The tether isinserted into a notch 765 (FIG. 60) on the front of the seat frame, withone of the stops engaging a top surface of the horizontal flange of theframe and being larger than the notch to prevent pull-through. Aplurality of stops are provided such that the tether can be set atdifferent initial lengths depending on the size of the seat.

A flexible body support member 138 has an upper first portion 140slidably/translatably connected to the seat, e.g., the suspended bodysupport member 70, for example with a plurality of fasteners, such astabs 141 received in an opening 143. As shown in FIGS. 47, 58, 59 and65, the flexible member has rearwardly extending strips 141 withoutboard, laterally extending flanges 139 that are received in openingsformed by laterally spaced upper platforms 165 and laterally spacedlower platforms 163. The lower platforms 163 are connected with a basefloor 167, with a vertical flange 169 extending upwardly from the basefloor to support the upper platform. The flanges 139 are received underthe outwardly extending portions of adjacent upper platforms 165, whilethe main body portion of the strip 141 is supported by the lowerplatform 163. In this way, the strips 141 are vertically supported, butalso allowed to translate or slide relative to the support layer 70.

The flexible member further includes a second portion 142 connected tothe carriage 118, with a third curved portion 144 (bullnose) positionedbetween the first and second portions and forming a leading edge of theflexible member. The flexible member is configured with a plurality oflaterally spaced and longitudinally extending slots 160 that define aplurality of longitudinally extending strips 162 as well as strips 141.The flexible member can be made from various plastic materials such aspolypropylene or polypropylene blended with KRATON. The flexible membercan be configured as a single, integrally formed member with the slotsformed therein, or as a plurality of independent, separate strips.Preferably, the widths and number of strips corresponds to the width andnumber of steps 124 formed on the leading edge 122 of the carriage. Thecarriage 118 is disposed behind or beneath the flexible member, with theleading edge 122 disposed adjacent to, and in one embodiment, engagingan inner surface of the flexible member, or alternatively a bottomsurface of the flexible member, and in particular the strips 162. In analternative embodiment, the leading edge of the flexible member on thethird portion thereof is generally curved in a forwardly convex shape,with the lengths of the strips 162 becoming progressively andindividually longer as they move inboard. The leading edge of the seatis defined by the forwardmost portion, or third portion of the strips162, with the understanding that a cover such as fabric could further bedisposed over the strips. In an embodiment where the forwardmostportions of the strips follows the leading edge of the carriage, theleading edge of the seat is non-linear, or convex.

A cover member 56, best shown in FIG. 17, is disposed over the entiretyof the seat, including the rear region 84 and the front region 62. Thecover member, preferably configured as a fabric and carrier member,wraps around the flexible member 138 and covers the third curved portion144 of the flexible member. The fabric is secured on all sides to thecarrier member including laterally extending member 165. The coverfurther includes a first fold 146, shown in FIGS. 16 and 17 as a pair oflaterally spaced tethers. As disclosed above, the carrier member candefine the first fold. In an alternative embodiment, the first fold isdefined by a portion of the fabric extending across the entire width ofthe cover. The free edge 152 of the first fold, or free end of thetethers (whether formed by the fabric or the carrier member, is anchoredto the front seat frame, for example with a rod 154, or to the notch 765as explained above. The first fold lies along an upper surface 156 of adriving member 158, or inboard of the cover 745. In one embodiment, thedriving member 158 is formed by rearwardly extending arm portions of theflexible member 138. In another embodiment, the driving member can beformed by the carriage member.

As shown in FIG. 57, the driving member is formed by the cover 745,which includes the bearing portion 761. The curved bearing portion 761of the driving member forms a folded edge 148 in the cover member (orcarrier member), with a second fold 150 underlying the driving memberand the first fold, or lying outboard of the first fold. It should beunderstood that the actual material of the cover defining the foldededge, as well as the length of the first and second folds, varies andshifts between the first and second folds as the carriage member 118 andconnected flexible member 138 move relative to the seat frame. As such,the folded edge 148, as well as the first and second folds 146, 150, aredefined by the material forming the edge and folds at any one time. Inthis embodiment, the tether, or portion of the cover forming the firstfold, is preferably non-elastic.

In operation, the user grasps the carriage member 118, e.g., the handles132, the cover 745, or the front portion of the seat such as theflexible support member or bullnose, and moves the carriage member to adesired longitudinal position defining a corresponding depth of theseat. Various detents or other locking/latching features can be formedon one of the carriage and seat frame to provide a plurality ofadjustment positions, or the adjustment can be simply arrested byfriction so as to provide an infinite number of adjustment positions.

As the carriage 118 is moved forwardly, for example, the third portion144 and leading edge of the flexible member 138 also move forwardly,with the length of the first fold 146 of the cover being shortened. Atthe same time, the upper portion 140 of the flexible member andcorresponding portion of the cover lying thereover lengthens, whichcorresponds to a greater overall seat depth. Conversely, as the usermoves the carriage 118 rearwardly, the drive member 158 moves the foldededge 148 rearwardly and thereby increases the length of the first fold146 as the third portion 144 and leading edge of the flexible member aremoved rearwardly, with a corresponding seat depth being reduced.

In an alternative embodiment, the rear edge of the cover or fabric issimply secured to the seat frame, tilt housing or other structure withan extensible, or stretchable tether, for example an elastic tether. Forexample, the tethers in FIG. 17 can be formed as elastic members. Inthis embodiment, the cover does not have a first fold. Rather, theelastic tether simply elongates or retracts as the carriage is movedforwardly and rearwardly respectively. In this way, the tether holds thecover against the body support member and allows it to slide past thefront, curved portion thereof when the seat depth is lengthened, butthen draws the fabric back under the seat as the seat depth isshortened.

The flexible strips 162, along with the stepped leading edge 122 of thecarriage, provides a varied suspension force for the user's thighs. Inparticular, at the region where the steps 128 are formed mostrearwardly, the corresponding strips 162 of the flexible member areallowed a greater amount of deflection in response to the weigh of theuser. These steps 128 and strips are generally aligned with thelongitudinally extending thighs of the user. Conversely, the flexiblemember 138 is more rigidly supported along the lateral centerline at thestep 126, and at the outermost lateral positions at steps 130, due tothe steps 126, 130 having a greater forward extent.

The cover 56 can be secured to the rear and front seat frames, as wellas the flexible member, with a carrier member 164, shown in FIGS. 6 and7, which engages for example and without limitation the fingers 54, 80formed on the seat frames.

Referring to FIGS. 81-84, in an alternative embodiment, a cover 800includes a rearward side wall portion 802, an upper flange 804 and alower flange 806. The upper flange 804 is coupled to the suspended bodysupport member 70, for example by bonding or with fasteners and like,while the lower flange is coupled to the seat frames 524, 572. A forwardportion 808 of the cover includes a curved grippable portion 810,forming a curved wall having bottom and front portions, and a channel812 formed laterally therethrough. A handle 814 includes a curvedgrippable portion 816 shaped to be received in the channel, and arearwardly extending shaft or post 818. The handle further includes aflange 820 extending laterally inwardly, which is secured to thecarriage 718. The post 818 extends rearwardly through a channel formedin and by the cover 800 and extends through an opening of the cover soas to increase the rigidity of the cover as shown in FIGS. 81 and 82. Anintermediate portion 822 of the cover includes an expansion or bellowsstructure, which allows the forward portion 808 to move fore and aft ina longitudinal direction relative to the fixed rear portion 802 of thecover. The expansion structure includes a plurality of vertical ribs 824connected with connection ribs 826, which allow the vertical ribs tomove from a minimum seat depth position, wherein the ribs 824 areproximate each other, to a maximum seat depth position, wherein the ribsare spaced from each other. The cover 800, including the expansionjoint, helps limit the access of the user to the interior of the seat,where various pinch points may be created. In addition, the cover 800provides an unique aesthetic and closure, while still permitting arelative movement or translation of the forward portion of the seat, forexample when adjusting the depth of the seat. As shown in FIGS. 100 and101, the cover 1800 includes a rear cover portion 1804 that closes offthe sides of the seat between the seat surface and the lower framemembers, and a front cover portion 1808 that is secured to the carriage,with the front cover portion sliding relative to the rear cover portionas the depth of the seat is adjusted. Either the front or rear portioncan be positioned exteriorly of the other during the relative slidingmovement.

Referring to FIGS. 85 and 86, in an alternative embodiment of the seatdepth mechanism, the cover member 826, for example a fabric member,includes a laterally extending wire 828 secured to edge portion of thefabric, for example by sewing or heat sealing the wire to the fabric, orby positioning the wire within a fabric loop. A pair of laterally spacedclips 830 are secured to the wire, and thereby to the fabric. Of course,it should be understood that the clips can be secured directly to thefabric without the wire, although the wire provides stability to thefabric as it is moved. A pair of tethers or strings 832 have a first endattached to a respective one of the clips. It should be understood thatthe tether or string can be secured directly to the cover, for exampleby bonding or sewing, or can be integrally formed therewith for exampleas an extension of the cover. In this way, the tether or string areconfigured as part of the cover or fabric. The strings or tethers extendrearwardly, through an opening 834 formed in a guide member 836. Thetether or string 832 slidably moves relative to the guide member throughthe opening at a folded portion 838 of the string, again forming aportion of the cover. An opposite end of each string is coupled to theseat frame 524, for example by securing a loop of the string to a hook840 on the frame. A spring 842 is disposed in a channel around a post844 formed in the spring guide, with the channel 846 which is furtherdisposed on a rearwardly extending tab 848 or protrusion of the flexiblemember 138, or lower portion 142 thereof. The connection of the two endsof the string 832 to the frame and the flexible member preloads thespring by urging the guide member 836 toward the flexible member 138against a biasing force of the spring 842. In this way, the string 834and spring 842 maintain the cover 826 in tension about the flexiblemember 138 as the flexible member is moved fore and aft between theminimum and maximum seat depth positions with the tether moving/slidingrelative to the guide.

Tilt Mechanism:

As shown in FIGS. 5, 10, 21-23 and 42-45, and as mentioned above, thehousing 2 includes a lower housing member 16 and an upper housing member14. A seat support bracket 166 has a pair of forwardly extending pivotarms 168 and a rear support platform 170. The support bracket 166 isconnected to the rear seat frame 72, and in particular is fastened tothe platform 170, such that the support bracket 166 forms part of thethird link. The pivot arms 168 are pivotally connected to the tiltcontrol housing at the fourth pivot axis 96. Each pivot arm has acurved, or arcuate, slot 171 formed therein, with the slot having agenerally vertical orientation.

A back support bracket 172 also includes a pair of forwardly extendingpivot arms 174 that are pivotally connected to the tilt control housingat the fourth pivot axis 96. The pivot arms also each have an arcuateslot 176 (or track) that are aligned with the slots 171 in the seatbracket. A forward stop member 178 (or guide) extends through the slotsand is secured to the tilt control housing. The brackets 166, 172 pivotabout the fourth pivot axis 96, with the stop member 178 engaging abottom of the slots 171, 176 to limit the forward pivoting or tilting ofthe seat and back in an upright, normal position as shown in FIG. 10.

A pair of tilt limiters 180, 780 are pivotally secured to the seatbracket about a pivot axis with a pivot member. The tilt limiters have aplurality of indexing detents 182 selectively engaged by a cantileveredspring 184 extending from the seat bracket. The indexing detents canalternatively be located along a side face of the tilt limiter. The tiltlimiters further have a plurality of steps 186 formed along a leadingedge thereof that are selectively engaged with an edge 188 on the tiltcontrol housing. In this way, the rear tilting of the seat bracket 166,and connected back support bracket 172, are limited by the pivotalposition of the tilt limiters 180 relative to the tilt control housing2. The pivotal location of the tilt limiters 180 is controlled by anactuator 190, configured as a cross tube, rotatably connected to theseat bracket. The actuator 190 includes a pair of lugs with slots 192,with the lugs being connected to corresponding slots 191 on the tiltlimiters 180. When rotated, the actuator 190 pivots the tilt limiters180 about pivot axis 196 to the desired position, with the indexingmechanism (detent 180 and spring 184) corresponding to the variousavailable positions of the tilt limiters.

In another embodiment, shown in FIGS. 39 and 42, the actuator 790 ispositioned more rearwardly, such that a lever or grippable portion 731on the actuator is disposed adjacent the location of the hand of theuser when their arm is relaxed and allowed to drop or hang vertically,i.e., at a “handfall” position relative to the user. As shown in FIG.39, the grippable portion is preferably positioned rearwardly of therear of the seat or alternatively in the rear 10% of the seat depth. Alink 791, generally Y-shaped, is connected to the actuator. End portionsor lugs 793 of the link are rotatably connected to a lever portion 795extending radially from the actuator, with arms 797 diverging outwardlyfrom the end portions and having opposite end portions rotatablyconnected to the tilt limiters 780. The seat bracket 166 is providedwith an opening 799, configured as a pair of slots, in the rear portionof the platform 170 that accommodate the lever portion 795 and lugs 793of the link. In operation, the user rotates the actuator 790 by way ofgrippable portion 731, which pivots the link 791 and thereby rotates thetilt limiters 780 to a desired position.

As best shown in FIGS. 5, 9 and 42-44, a fulcrum assembly 200 ismoveably installed in the tilt control housing beneath a pair of leafsprings 202. The leaf springs are preferably made of a compositematerial, such as a fiberglass and epoxy matrix, although it should beunderstood that other resilient materials such as steel would also work.The composite material can be a fibrous composite, a laminated compositeor a particulate composite. A suitable composite spring is commerciallyavailable from Gordon Plastics, Inc. of Montrose, Colo. under thespecification designation of GP68-UD Unidirectional Fiber Reinforced BarStock, and sold under the tradename POWER-TUFF. The fiberglass/epoxymatrix bar preferably is unidirectional with a glass content of about68% and a laminate density of 0.068 lbs./in.³. The bar preferably has aflexstrength of about 135,000 psi, a flex modulus of about 5,000,000psi, and an ultimate strain of about 2.4%. The use of a compositematerial bar can help eliminate the problems associated with creep.Another suitable spring is uni-directional fiberglass 70±2% by weight30% vinyl esther hi-performance resin. The shape, size (width,thickness, length) and material of the springs can be varied to providevarious spring characteristics. In addition, the spring can becompression molded in various curved shapes to provide unique tiltbalance and ride options. In one embodiment, each spring isapproximately 9.25 inches long, 1.85 inches wide and 0.225 inches thick.

In operation, one end 204 of the leaf spring 202 directly biases theback support bracket 172, via a laterally extending rod 218 secured tothe back support bracket, and indirectly biases the seat support bracket166 via the back support bracket in an upward direction so as to therebysupport a user sitting in the chair. The opposite end 206 of the springengages a cross member 208, configured with openings 212 and a pair oflocator tabs 210 disposed in openings 216 formed in the springs 202. Thecross member is disposed laterally across a front portion of thehousing, while an intermediate portion of the spring is supported by thefulcrum member 214. In this way, the springs 202 act as a simplysupported beam with a load imparted intermediate the supported endsthereof. To adjust the force applied to the back support, the user movesthe fulcrum assembly 200 in a linear, longitudinal direction within thehousing. It should be understood that the spring biases the seat supportby way of the back support, and that in alternative embodiments, thespring can bias the back support and seat support through a commonelement, such as with a pivot member that pivotally connects thosemembers, or can directly bias the seat support and also the backsupport. In any of these embodiments, it should be understood that thesprings are biasing each of the seat support and back support,individually and in combination.

As the fulcrum assembly 200, including fulcrum member 214, is movedrearwardly in the housing 2, the distance between the point of supportat the fulcrum member 214 and the support member 218 is decreased, so asto correspondingly increase the force applied by the rear end 204 of thespring. Conversely, the fulcrum member 214 can be moved forwardly in thehousing 2 to decrease the amount of resistive force applied to the seatsupport bracket 166 and back support bracket 172 by increasing the beamlength, or the distance between the fulcrum member 214 and the supportmember 218. Since the leaf springs 202 are simply supported at each end,rather being clamped to the housing 2, the pivot rod 218 or both,bending moments are not introduced at the ends of the spring. Whenclamped, the properties of the spring, and the amount of the clamping,can effect the loading and associated stresses. Moreover, by providing asimply supported spring, tolerances can be relaxed and the curvature ofthe spring is allowed to undulate as the beam length changes.

Because the leaf springs 202 are disposed in the housing 2 in aside-by-side arrangement, and are preferably formed as flat bars, thehousing can be made more compact at lower cost in an aestheticallypleasing way. Moreover, the resistive force of the spring can beadjusted easily and simply by slideably moving the fulcrum assembly 200within the housing 2. Since the resistive force is determined by thebeam length, rather than by prestressing the spring, the adjustment doesnot require a progressively larger actuation force as is typicallyassociated with torsion springs and bars and compression springs.

Referring to FIGS. 5 and 11, the end 204 of the spring is configuredwith a cam 220 having a concave cam surface 222. FIG. 11 shows thespring in two different biasing positions. The cam surface is formed onan upper surface of the spring. The cam can be integrally formed as partof the spring, or separately configured and connected to the springwith, for example and without limitation, rivets or other mechanicalfasteners, adhesives, etc., or any combination thereof. The back supportbracket 172, and in particular the rod 218, is configured with a camfollower 224 having a convex cam surface 226. In an alternativeembodiment, shown in FIGS. 42 and 43, a separate cam follower isomitted, with the rod 218 itself functioning as the cam follower (ordriver), and having a cam surface 227. As the user tilts rearwardly, thecam follower (or driver) 224, 218 rides along the cam 220 with the twocam surfaces 222, 226, 227 contacting each other, such that the camfollower slides rearwardly along the cam surface 222, which drives moredeflection into the spring as compared with a flat spring surface. Thishas the effect of increasing the spring force applied by the spring,which corresponds to an increased torque as the angle of reclineincreases. In this way, the spring, fulcrum and cam, in combination,provide a balanced ride to the user.

In particular, a balanced ride is achieved for all of the users.Typically, the greatest imbalance will be for a light user at the fullrecline position and for a heavy user in the forward position. It mustbe understood that the user will necessarily need to initially adjustthe fulcrum member to achieve a balanced ride at any particular reclineangle, but that thereafter, the ride will be substantially balancedthroughout the defined tilt range without further adjustments of thefulcrum. As such, the chair provides a unique balanced ride that avoidsthe user having to readjust the biasing force depending on the angle ofrecline in which they want to user the chair.

It should be understood that, in one embodiment, the applied torque andrestoring torque are simply loads being applied over a distance.Accordingly, the balanced ride can also be thought of in terms of anapplied force being applied by the user to the body support member at acertain location. Various aspects of the springs and tilt mechanism, oralternative embodiments thereof, are disclosed for example and withoutlimitation in US Pub. No. 2004/0183350A1, which is hereby incorporatedherein by reference.

Referring to FIGS. 5, 9, 18-20, 40, 41 and 44 the fulcrum assembly 200and fulcrum, otherwise referred to as a force adjusting member, includesa base housing 228, an intermediate housing 230, 830, and an upperhousing 232, 832. The base housing 228 is configured with a pair oflaterally spaced cavities 234 open at both the top and bottom thereof.The base housing also includes a centrally located recess 236 and frontand rear walls 238, 240 forming at least a portion of pair oflongitudinally spaced openings 242, and one each of a longitudinally andlaterally oriented gear recess 244, 246. A pair of laterally extendingrollers 248, 250 is disposed in each cavity. The lower roller 250 ineach cavity 234 is in contact with the floor 252 or support surface ofthe housing, while the upper roller 248 in each pair extends above thesurface of a side portion 254 of the base member defining the cavity,such that the curved surface of the roller is in contact with a bottomsurface of a corresponding spring 202.

A driven bevel gear 256, disposed in the longitudinally oriented gearrecess 244 in the base housing, is threadably engaged with alongitudinally extending lead screw 258 non-rotatably secured to a frontof the tilt housing, for example with a flange having a button thatfaces the housing and snaps into an opening formed in the housing. Thelead screw 258 extends through the longitudinally extending openings242. A thrust washer 260 and bearing 262 are disposed between the bevelgear and a rear surface of the rear wall 240 of the base housing 228 soas to allow the bevel gear to easily rotate about the lead screw. Abottom of the base housing is configured with a follower 264 or guide,shown as two posts in FIG. 66, which slides in a track 266 formed in thebottom of the tilt housing.

A laterally oriented drive bevel gear 268 engagingly meshes with thedriven bevel gear 256. The drive bevel gear 268 is further integrallyconfigured with, or otherwise connected to, an idler gear 270 disposedon an opposite side of the bevel gear. The intermediate housing 230, 830traps or encases the bevel gears 256, 268 between the intermediatehousing 230, 830 and the base housing 228, and further includes a pairof longitudinally spaced openings 270 that surround the lead screw 258between the housing components.

A drive pinion gear 272 is disposed in a gear recess 274 formed in theintermediate housing above the idler gear 270. The drive gear 272engagingly meshes with the idler gear 270. The intermediate housing 230is configured with a laterally extending opening 276, or half opening,that supports an actuator shaft 278. An end of the shaft 281 and thedrive gear are configured with mating D-shaped ends/openings 280, suchthat rotation of the shaft rotates the drive gear. The shaft and drivegear are disposed between the intermediate housing 230 and the upperhousing 232, which is also configured with a gear recess 282 and alaterally extending shaft opening 284. As mentioned above, in theembodiment of FIGS. 5 and 9, a lever arm 108 is pivotally securedbetween the upper and intermediate housings and is pivotable around avertical axis 288. An end portion of the arm 112 is aligned with theaxis of the actuator shaft extending through the drive gear. Theintermediate housing is configured with a cable housing stop 286, suchthat a cable can be secured to an opposite end of the lever.

Alternatively, in the embodiment of FIGS. 40, 41 and 44, the cable istranslated by the pivoting action of the joy-stick, thereby avoiding theneed for the lever arm. As shown in FIG. 44, a retainer clip 281rotatably engages a circumferential groove formed on the shaft 278, withthe clip engaging the intermediate housing with a snap fit so as toprevent the shaft from moving laterally relative to the fulcrumassembly.

In operation, the user rotates the actuator 278 (configured with agrippable member 290) about a laterally extending axis 294, which inturn rotates the drive gear 272. The drive gear rotates the idler gear270, which rotates the bevel gear 268 about a laterally extending axis292 parallel to axis 288. The bevel gear 268 rotates the bevel gear 256about a longitudinally extending axis 294, which threadably engages thelead screw 258 and moves the entire fulcrum assembly 200 in first orsecond opposite longitudinal (fore-aft) directions 52 to one of ainfinite number of predetermined force applying positions. For examplethe actuator can be moved between first and second adjustment positionsso as to move the force adjusting member (fulcrum assembly) betweenfirst and second force applying positions. It should be understood thatthe actuator 278, 290 and fulcrum 214 are infinitely adjustable to aninfinite number of adjustment positions and force applying positionsrespectively.

As the actuator 278, 290 is rotated and the fulcrum assembly 200 movedin one of the first and second longitudinal directions, the actuator issimultaneously translatably moveable relative to the tilt housing withthe fulcrum assembly. In this way, the operator is provided with visualindicia about the relative biasing force that will be applied by thesprings 202 simply by viewing the position of the actuator 278, 290relative to the tilt housing 2. In one embodiment, a scale or otherindexing indicia (e.g., text “heavy”, “medium” or “light” or colors(green for light to read for heavy)), is provided on the housing tofurther aid the operator in ascertaining the predetermined setting ofthe force applying member. A cover can be disposed around the housing,and be provided with a longitudinally extending slot in which the shaft278 travels. Alternatively, as disclosed in FIG. 61, a cover candisposed beneath the shaft, with the upper housing of the fulcrumassembly extending upwardly through a longitudinal opening formed in thecover.

It should be understood that the biasing mechanism can also be used withother springs, such as torsion coil springs tension/compression springs,etc. For example, an actuator acting on an arm of a torsion spring, oragainst the force of a compression/tension spring, can be moved relativeto the housing to provide a visual indicator to the user of the settingof the force applying member before (or while) the user is seated.

Backrest:

Referring to FIGS. 1-4B, 18-38, 42 and 45-54, a back support memberincludes lower support member 172, configured as the back supportbracket referred to above, pivotally connected to the base tilt housingat the pivot axis 96 and an upper support member 294 pivotally connectedto the lower support member about a horizontal pivot axis 296 spacedrearwardly from the pivot axis 96. An adjustment mechanism 298 iscoupled between the lower and upper support members 172, 294. At leastone backrest component 300, shown in one embodiment as a frame 302, isconnected to the upper support member 294 adjacent a thoracic region ofthe backrest component. A lower portion 304 of the frame 302 is fixedlyconnected to the seat frame 72 along a rear edge thereof. The upperportion of the backrest is flexible relative to the lower portionthereof, as the upper support member pivots about the axis 296. In analternative embodiment, the upper portion of the frame is pivotallyconnected to a lower portion. In the embodiment of 2-4B, a lower backsupport 303 is connected to and extends upwardly from a rear of the seatframe and is secured to the back frame, or backrest, at a lower portionthereof, for example at the lumbar region. The upper support member 294,together with the backrest 300 and frame 302, can be easily removed ordisconnected from support member 172 in a knock-down configuration forshipping.

The adjustment mechanism 298 is operable between a plurality ofpositions, including for example and without limitation a first andsecond position, and is infinitely adjustable. The upper support member294 is pivotable relative to the lower support member 172 about thehorizontal axis 296 between a corresponding plurality of static supportpositions as the adjustment mechanism is operated. In variousembodiments, the upper support member (and an upper body support surfaceof the back) is pivotable relative to the lower support member (and alower body support surface of the back) about 10 degrees from aforwardmost position to a rearwardmost position. In other embodiments,the upper member is adjustable between about 1 degree and 15 degrees,more desirably between about 5 degrees and 15 degrees, and preferablyabout 10 degrees between the forwardmost and rearwardmost positions.

The upper support member includes a spine member 306 and a bracket 308disposed and secured in a bottom portion of the spine member. In oneembodiment, a tab 310 engages the spine to prevent rotation of thebracket relative to the spine. The bracket can be formed integrally withthe spine, or as a separate member. The bracket includes a pair offorwardly extending flanges 312 with openings defining the pivot axis296. The flanges are pivotally connected to the back support bracket 172with a pair of pivot pins 314.

A lower housing component 316 is secured to a support platform 317 onthe back support bracket 172. The housing component 316 is configuredwith a lower wedge surface 318. A cover member 320 is secured to thelower housing component, with the cover and lower housing defining apassageway 322 for a rotatable actuator shaft 326, which travels in aslot 319 formed in the bracket 308. An acme shaft 324 is rotatablymounted in the lower housing. Mating ends 328 of the actuator shaft 326and acme shaft 326 are configured with D-shaped cross-sections, with amoveable collar 330 disposed over the ends to secure the actuator to theshaft. The collar 330 can be translated in a lateral direction 52 torelease or lock the ends of the shafts.

In an alternative embodiment, shown in FIG. 45, the lower housingcomponent 916 includes a resilient flexible tab member 918 having catchportion. The housing component can be secured to the support bracketwith one or more tabs or hooks, for example with a snap fit. The tabmember 918 flexes upwardly as the shaft 324 is inserted through anopening in the lower housing component until the catch member engages acircumferential groove 920, or undercut, formed in the shaft. The endportion 922 of the shaft is formed with a key shaped cross-section, suchas a hexagonal cross section, and engages a mating cross-section formedby a socket 924 on the acme shaft 926. The acme shaft is insertedthrough an opening in the housing component 916, with a head 928 of theshaft engaging an end wall of the lower housing component. A torsionspring 930 has a first down-turned end 932 engaging an opening 938formed in a platform of the lower housing component. A pair of tabs 940rotatably engage an elongate shaft portion of the spring, while a bentend portion 934 of the spring extends rearwardly such that it engagesthe top surface of a flange 942 extending forwardly from the uppersupport member. The spring can be preloaded before assembly by engagingit with a catch member 935.

An upper wedge member 332 is disposed over the shaft 324 and includes aslot or socket 336 engaged with a drive member 338, configured as anacme plate threadably engaged with the shaft 324. The drive member 338can be formed integrally with the upper wedge member or as a separatepart, but is considered part of the wedge member in either embodiment.The upper and lower wedge members 316, 332 are configured with opposingwedge surfaces 318, 334 that slide along each other and force the wedgemembers apart, and in particular, forces the upper wedge member uprelative to the lower wedge member as the upper wedge member translatesin a lateral direction 52 relative to the lower wedge. It should beunderstood that in an alternative embodiment, the upper wedge is fixedto the upper support member, and the lower wedge member is translatablymoveable in the lateral direction. The upper wedge member 332 has anupper surface 340 that bears against an interior surface of the bracket308 and causes the upper support member 294 to rotate relative to thelower support member 172 about axis 296 as the wedge members are forcedapart. As shown in FIG. 18, a compression spring 342 is disposed betweena stop 344 formed on the upper support member, and in particular thebracket 308, and a stop member 346 extending upwardly from the backsupport bracket. The spring 342 biases the upper support member awayfrom the back support bracket, or lower support member (clockwise asshown in FIG. 18). In essence the spring 342 biases the bracket 308against the upper surface of the wedge member 340

In operation, the user rotates the actuator 326, and in particular agrippable portion 348 thereof, in a first or second rotationaldirection, which causes the shaft 326 to rotate and thereby moves thedrive member 338 and associated upper wedge member 332 laterally. Asshown in FIGS. 21-23 (and 50, 49 and 48), the upper back support 294 ispositioned respectively in a forward, neutral, upright position, anominal, neutral, upright position and a rearward, neutral, uprightposition relative to the lower back support 172. In particular, the gapbetween the back support 294 and the bottom of the seat frame or bracket168 widens as the back support is pivoted rearwardly to the desiredupright position (forward, nominal or rearward), with the angle betweenthe body facing surface 98 of the seat and the body facing surface 340of the back being adjustable. As the wedge surfaces 318, 334 slide pasteach other, the upper back support 294 is pivoted relative to the lowerback member 172 to a desired setting. Preferably, the actuator 326,configured with the grippable member 348, extends laterally outwardlyadjacent a side portion of the seat, or rearwardly thereof, and inparticular adjacent or rearwardly of a rear side portion of the seat,such that it is readily accessible to a user seated in the chair. Inthis way, the initial upright setting of the backrest can be adjusted toaccommodate different users with different back and spinalpostures/curvatures. This adjustment of the initial angle of thebackrest is independent of any of the kinematic/dynamic movements of thebackrest relative to the seat, but rather is a static fit adjustment. Assuch, the forward, nominal or rearward adjustment is then heldthroughout the tilt range of the chair, for example from the uprightposition through the intermediate tilt position to the full tiltposition.

In addition, the backrest is provided with a mechanism that allows anupper portion 354 of the back to pivot or flex relative to a lowerportion 304 of the back between a neutral position and an extendedposition, as shown in FIGS. 3D, 15 and 54. The ability of the upperportion to pivot relative to the lower portion is independent of thetilt position of the back. The upper portion 354 is pivotable relativeto the lower portion when the tilting of the lower portion is limited orrestrained, for example when the pivotable movement of the seat frame 72or bracket 166, which is fixedly attached to the lower portion 304, islimited. In some instances, the upper portion may be pivotable or flexedto an extended position even when the seat frame or bracket is notrestrained, for example when the position or weight of the user balancesthe seat such that it does not pivot rearwardly against the biasing theforce of the springs.

As explained above, the rear tilting of the seat bracket 166 is limitedby the position of the tilt limiter 180 or stop member 178 relative tothe tilt control housing 2. For example, as shown in FIGS. 18 and 19,the seat is tilted rearwardly from an upright position to a reclinedposition, wherein the tilt limiter 180, or the engagement of the stopmember 178 in the top of the slot 170, prevents further recline of theseat. At this juncture, the use can arch their back, or stretchrearwardly so as to move or pivot the upper portion 354 of the back andupper back support 294 rearwardly relative to the lower portion of theback frame 302 and the seat bracket 166. As the user biases the upperportion 354, the lower back support 172 pivots away from an engagementwith the seat bracket 166 against the force of the springs 202, whichact of the lower back support 172 as shown in FIGS. 5 and 20. In thisway, a single biasing assembly (the pair of leaf springs) biases theseat and back during normal use of the chair, and biases only the upperportion of the back by way of the bracket 172 and support 294 during theextension use of the chair, with the seat being supported by the tiltlimiter 180 or stop member 178. In various embodiments, the upperportion can be pivoted relative to the lower portion, or the uppersupport relative to the seat bracket, between about 2° and 10°, anddesirably about 6°.

In essence, the back has three levels of adjustment/range of motion: (1)tilt range—from upright through intermediate recline to full recline(can be arrested in various positions by a tilt limiter); (2) back angleadjustment—from forward to nominal to rearward (independent of tiltrange); and (3) thoracic adjustment—neutral v. extended (independent oftilt range and back angle adjustment). The back preferably has a tiltrange of about 4° to 22°, and more desirably about 18°. It should beunderstood that the back is infinitely adjustable throughout the tiltrange and back angle adjustment, and is not limited to the threepositions listed for each. For example, the tilt range includes aninfinite number of intermediate recline positions, although the seatingstructure can be arrested in a limited number of such positions asdefined by the steps of the tilt limiter. Likewise, the back angleincludes an infinite number of nominal positions between the forwardmostand rearwardmost positions. Finally, the user can move the thoracicregion through a continuous range of positions from the neutral toextended positions, particularly when the seat is restrained by the stopor tilt limiter.

Referring to FIGS. 24-26, 34, 37, 46 and 48, and as mentionedpreviously, the upper support member 294 includes a spine 306 extendingupwardly along a centerline of the back. A pair of arms 356 extendlaterally outwardly and upwardly from the spine. A plurality of teeth ortabs 357 extend from the arms for engagement with a carrier member orother covering. The spine is preferably made of aluminum, steel,fiberglass, composites, plastic, or some other rigid but resilientmaterial. The spine can be made of various materials, such as Capron8233G—33% Glass Filled Nylon 6.

The ends 358 of the arms are pivotally secured to upper corners 364 ofthe frame member 302 about a horizontal pivot axis 360. The frame 302can be made of various plastic, metal or composite materials, includingfor example and without limitation a nylon material, or a nylon,elastomeric material. An upper thoracic region 362 of the spine isfixedly secured to a first cross member 366 of the frame, for examplewith screw or other mechanical fasteners, with the first cross memberbeing longitudinally spaced from a top cross member 368 of the frame. Asshown in FIGS. 34, 39 and 46-48, the thoracic region 362 is configuredwith four lugs or flanges 363 that are secured to the cross member 366with a connector member 365. In one embodiment, as shown in FIGS. 62 and67, a pair of flanges extend rearwardly from the cross member 366. Theflanges formed a generally U or V shape in cross section. The connector365 can be formed integrally or separately from one or both of the spine294 and frame 302. Likewise, the thoracic region can be directly securedto the cross member 366 or other component of the frame 302. Second andthird cross members 370, 372 are further longitudinally (vertically)spaced between the first cross member and a bottom portion 304 or crossmember, which is fixedly secured to the seat frame, as explainedpreviously. The first and second cross members 366, 370, and the thirdand bottom cross members 372, 374 are each connected with a centrallylocated connector member 376, 378. Likewise, the second and third crossmembers 370, 372 are connected with a pair of laterally spaced connectormembers 380 spaced sideways from the centerline of the back frame.

A number of whiffle structures, or levers rotatable about anintermediate fulcrum, are coupled to the frame, or are integrally formedas shown in FIG. 96 as part of the frame without side frame members orportions of cross members extending to the side frame members. Forexample, a first series of longitudinal levers 382 extends (vertically)from the first cross member in the thoracic region, with the first crossmember 366 providing some torsional resistance as the levers rotate inopposite first and second directions about an axis defined by the firstcross member. A second series of levers 384 extends laterally from eachend of each of the first series of levers, with the first series oflevers each providing torsional resistance as the each of the secondseries of levers rotates in opposite first and second directions. Athird series of levers 386 extends laterally from each end of the secondseries of levers 384, again with the second series of levers providingtorsional resistance as each of the third series of levers rotates.Finally, a fourth series of levers 388 extends laterally from each endof each of the third series of levers with the same torsionalrelationship. Each end 390 of each of the fourth series of levers isconfigured as a node, with an attachment location configured to beconnected to an individual pad. A plurality of the pads are connected toform a unitary pad structure, shown in FIG. 35.

Referring to FIG. 34, a first series of levers 394 extends laterallyfrom the central connecting members 380, with an outer leg being longerthan an inner leg of each of the first series of levers. A second seriesof levers 396 is secured to each end of each of the first series oflevers, while a third series of levers 398 is secured only to the endsof the outer second series of levers 396. The inner second series andthe third series of levers are each configured with a node 390 at theend of the lever.

Finally, a first series of levers 400 extends laterally from a pair ofrelatively rigid arms 402 extending longitudinally upwardly from thebottom cross member 304, with an outer leg being longer than an innerleg of each of the first series of levers. A second series of levers 404is secured to each end of each of the first series of levers, while athird series of levers 406 is secured only to the ends of the outersecond series of levers. The inner second series and the third series oflevers are each configured with a node 390 at the end of the lever.

Of course, it should be understood that various configurations oflevers, with varying numbers of series, can be used to support the backof the user. The preferred embodiment shown in FIG. 34 provides variousadvantages.

For example, in one alternative embodiment shown in FIGS. 87-91, 96 and97, portions of the cross-members and side frame members are omitted. Inthis embodiment, the arms 900 are formed as a separate antler structure,which is pivotally coupled to the spine 902 with a shaft or axle 904about a pivot axis 906. A pair of bushings 908, 910 supports the shaftin each of the spine and antler structure. The ends of the shaft 904 arecaptured in a cap member 912, which is coupled to the lever frame 950structure, for example with a pair of screws. Of course, it should beunderstood that the shaft 904 could be coupled to any of the threemembers (spine 902, antlers 900 or lever frame structure 950), androtatable relative to the others thereof. In addition, the shaft can besecured to lugs formed in any of the three members, or the shaft can beintegrally formed on one of the three members. In any event, the leverframe structure 950 and the antler structure 900 are allowed to pivotrelative to the spine 902 about the pivot axis 906. The ends 914 of theantler arms are pivotally secured to a cross member 952 extendingbetween and laterally outwardly from upwardly extending end portion ofthe outboard levers 982, as shown in FIGS. 96 and 97. A pin 916 or screwis snap fitted to secure the ends 914 of the arms to the cross-member952, with the arms pivotally bearing on the cross member. Alternatively,as shown in FIG. 89, the ends of the arms 926 can be configured with thecross member 928, which is pivotally secured to the ends of the leverarms 982. In one embodiment, shown in FIG. 89, the spine includes slots920, which receive lug members 922 extending forwardly from the antlerstructure and pivotally engaging the shaft 904 about the pivot axis 906.The cover 930, when disposed over the antler structure, forms a rearhood member. The upper thoracic portion of the backrest and hood isallowed to rotate about the pivot axis, thereby conforming to theposition of the body of the user as the user tilts rearwardly in thechair.

Each of the cross members, connecting members and levers 366, 370, 372,378, 380, 376, 382, 384, 386, 388, 394, 396, 398, 400, 402, 404, 406,982 are preferably configured with a U-shaped cross section. The centralportion of the second cross member 370 is further configured with aplurality of ribs 408 that increase the torsional stiffness of the crossmember 370, making it more resistant to twisting about a laterallyextending axis thereof. In this way, the upper regions of the back,defined between the third cross member 370 and the top cross member 368tend to rotate or twist about the third cross member, which has lesstorsional stiffness than the second cross member 370. At the same time,the central connecting member 378 also provides a virtual hinge alongthe two ends thereof where it is coupled to the cross member 372 and thecross member 374. The members 402 are relatively rigid, therebymaintaining a relatively rigid lower region of the backrest. As such,when the user extends their back by rotating the upper portion 354 ofthe back, and pivoting the back support 294, the upper portion tends tobend or rotate about the third cross member. At the same time, each ofthe individual levers can twist or rotate in response to the movement ofthe user and provide a balanced support for the user's back. As the userrotates upper portion 354, the lower portion 304, for example at levers406, does not flex or rotate, thereby providing firm support for thelower back and sacral region of the user. At the same time, the lumbarregion bends or rotates proportionally to the distance between the lowercross member 374 and the upper cross member 366, thereby providingintermediate support to the lumbar region of the user's back.

Referring to FIGS. 35 and 35A, the pad structure 416 is integrallyformed with a plurality of pads 392 corresponding to the number of nodes390 formed at the ends of the lever structures. A series of slots areformed between the individual pads to allow each pad to flexindependently with the corresponding lever node, while maintaining someconnectivity between the pads and nodes. In one embodiment, each pad isseparated along each side thereof from another pad by a pair ofelongated slots or slits 418, and two pairs of spaced apart sets ofthree slits 420, 422. The pair of elongated slits are disposed betweenthe three slits in each set. The middle slit 422 in each longitudinallyand laterally extending set extends across the entirety of the junctionbetween pads and forms part of the middle slit in adjacent sets of thethree slits. In addition, the outer slits 420 of the laterally extendingsets extend across the entirety of the junction between pads and formspart of the outer slits in adjacent sets of the three slits. The slitsform connectors 426 that resemble FIG. 8 structures, with the top andthe bottom of the “8” connected to the pad.

At an approximate mid point of the pad structure, i.e., the portionoverlying the second cross member 370, the pad structure transitionsfrom six pads extending laterally across the backrest to eight padsextending laterally across the backrest, with four centrally locatedpads above the cross member transitioning to two centrally located padsbelow. In this transition area, a lower, outer third slit 430 is madeshorter, and the upper laterally extending slit is split into two slits432, with the third middle slit 434 not extending into the lower padstructure. Additional decorative openings can be formed in each pad. Forexample as shown in FIGS. 68-70 and 95, alternative pad structures areshown. In FIG. 68, S-shape strips 661 connect adjacent pads.

A rear side of each pad is provided with a socket 438. As best shown inFIG. 46, a rubber grommet 440 is disposed between each pad and acorresponding node 390 of the lever. In one embodiment, the padstructure is formed by a two-shot mold process, with the pad formed, anda rivet molded onto the pad. Conversely, the lever arm can be made froma two-shot mold process. In other embodiments, the pad and frame can bemade by way of a two-shot or three-shot process.

For example, in a three-shot process, and referring to FIG. 71, acompliant material 395 is molded (but not bonded) onto the back side ofthe molded levers and through an opening 393 in the node 390. The padstructure is then molded and bonded to the resilient material 395. Inoperation, the pad 392 flexes relative to the node 390 by way of theresilient material.

Referring to FIG. 72, a two-shot process includes forming a socket 397in the resilient/compliant material 395. A post 399 formed on the backside of the pad is engaged with the socket by way of snap-fit.

Referring to FIG. 73, another two-shot process includes forming anelongated post 381 that extends through the compliant material and to afront side of the pad 392. The end 383 of the post is deformed, forexample by way of heat stake, so as to secure the pad to the resilientmaterial, which also forms an outer post mating with an opening in thepad.

Referring to FIG. 74, instead of using a resilient/compliant material,the pad structure is provided with a geometry that permits rotation orpivoting of the pad relative to a post 381 of the lever node. Inparticular, the through opening 385 in the pad is tapered or providedwith a frusto-conical such that the opening is larger on the front sideso the pad can rotate relative to the post. An end 383 of the post isagain deformed to secure the pad to the post. A recess is formed in thepad to receive the deformed head and form a flush surface.

Referring to FIG. 75, a post 371 extends rearwardly from the pad 392.The post can be formed form a compliant, resilient material. The postextends through a socket 373 formed in the lever node 392, with thesocket having a tapered or frusto-conical shaped geometry permittingrotation or pivoting of the post relative to the socket. An end portionof the post 371 can be deformed, for example by heating, to secure thepad structure to the frame 302.

Referring to FIG. 76, the pad structure is provided with a supportnodule having an exterior spherical shaped support surface 363 and athrough opening 365 with a tapered or frusto-conical shape. The lever ornode 392 is provided with a post 361 and a circumferential or annularsupport rim 367 having a tapered or rounded shoulder that slidesrelative to the exterior surface 363 of the nodule. The exterior surface363 and the shape of the through hole 365 permit rotation or pivoting ofthe pad relative to the lever. The end of the post 361 is deformed tosecure the pad to the frame 302.

Referring to FIGS. 1 and 37-38, an outer cover 442, such as a fabriclayer, is disposed over the body side surface of the pad structure. Acarrier member 444 is secured to the peripheral edge of the cover and isengaged with a ribbed peripheral edge 446 of the frame and the arms 357of the back support to secure the cover to the back. In an alternativeembodiment, shown in FIGS. 55A and 55B, a cover having a primary webmember 447 is secured to an elastic web component 449, for example bystitching with the seam directed inwardly away from the body-facingsurface. The web component 449 in turn has an edge portion 451 thatengages the peripheral edge of the frame, whether on the back or theseat.

Referring to FIGS. 91-94, where the whiffle structure does not have anyside frame members, the fabric is instead secured to the pad structure990 and lever frame 950. In particular, an edge portion 992 of theoutermost pad structure is stepped down from the remainder of the padstructure. An attachment strip 996 is secured to the fabric or outercover 930, which wraps around the strip and includes an edge portiondisposed between the strip and pad structure. The fabric can be furthersecured to the strip, for example by bonding, stitching, snaps or othermechanical fasteners, or combinations thereof. The end of the lever ornode 390 includes an opening or channel therethrough. One portion of theopening 994 includes a ramped portion 1002 formed along a side thereof,with the ramp progressively traversing toward the center of the channel.A recess or void 1004 is positioned on the other side of the channelfrom the ramp. A catch portion 1006 of shoulder is formed around thebottom of the channel. A fastener 1008 or pin includes a tapered headportion 1114 mating with a tapered mouth 1110 formed in an opening ofthe fabric strip 996, and a pair of enlarged annular portions 1112 thatare disposed in an upper, substantially cylindrical portion of theopening formed in the lever node. The pin further includes a bottom head1116 portion, or catch, which engages the catch 1006 of the lever with asnap-fit engagement. During installation, the bottom head 1116 slidesalong the ramp 1002 with the shaft of the fastener bending as the headis biased into the recess 1004 formed opposite thereof until the head1116 slides past the catch, with the head then snapping back intoengagement with the catch portion. In this way, the fabric strip 996 andfabric are secured to the whiffle structure, while providing anaesthetically pleasing and flexible edge. The pad structure 990 includesan opening 994 shaped to received an end or post portion of the node.The node includes an annular shoulder 1120 having a catch portion 1122disposed around the end or post portion, which engages a bottom or rearsurface of the pad structure. When installed, the pin 1008 sandwichesthe pad structure 990 and cover 930 between the fabric strip 996 andwhiffle structure 950. The opening 994 in the pad structure can beelongated or slotted in at least one direction (e.g., vertical), asshown in FIGS. 94 and 95, so to allow relative motion between the padstructure 990 and whiffle structure 950. In addition, as shown in FIG.95, the slits 1124 defining the pads do not extend to the edge of theoverall pad structure along the sides and top thereof, so as to providesome additional rigidity to the edge portion of the pad structure, forexample where the fabric strips are attached. In addition, the slits donot carry through laterally along the bottom of the pad structurebetween at least the center four pads of the first two rows, orlongitudinally between the four pads of the center columns, such thatthe lower sacral area thereof is provided with additional rigidity.

Although the present invention has been described with reference topreferred embodiments, those skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. As such, it is intended that the foregoingdetailed description be regarded as illustrative rather than limitingand that it is the appended claims, including all equivalents thereof,which are intended to define the scope of the invention.

1. A seating structure comprising: a support structure; a carriagemoveably supported by said support structure, wherein said carriage ismoveable relative to said support structure in opposite first and secondlongitudinal directions; and first and second flexible body supportmembers defining at least in part a seat, said second body supportmember coupled to said support structure, and said first body supportmember having a first portion moveably coupled to said second bodysupport member wherein said first portion is moveable relative to saidsecond body support member in opposite first and second longitudinaldirections, a second portion coupled to said carriage, and a thirdcurved portion positioned between said first and second portions,wherein said third portion is moveable toward and away from said supportstructure as said carriage is moved relative to said support structurein said first and second directions respectively.
 2. The seatingstructure of claim 1 wherein said carriage is translatably moveablerelative to said support structure.
 3. The seating structure of claim 2wherein said carriage is translatably coupled to said support structurewith at least one slide member.
 4. The seating structure of claim 1further comprising a cover member disposed over an outer surface of saidbody support member and covering said third portion of said body supportmember.
 5. The seating structure of claim 4 wherein said cover membercomprises a first fold anchored to said support structure.
 6. Theseating structure of claim 1 wherein said body support member has aplurality of longitudinally extending slots defining a plurality oflongitudinally extending strips.
 7. The seating structure of claim 6wherein at least one of said plurality of slots has a different lengththan at least one other of said plurality of slots.
 8. A seatingstructure comprising: a support structure; a carriage moveably supportedby said support structure, wherein said carriage is moveable relative tosaid support structure in opposite first and second longitudinaldirections; a flexible body support member having a first portioncoupled to said support structure, a second portion coupled to saidcarriage, and a third curved portion positioned between said first andsecond portions, wherein said third portion is moveable toward and awayfrom said support structure as said carriage is moved relative to saidsupport structure in said first and second directions respectively; anda cover member disposed over an outer surface of said body supportmember and covering said third portion of said body support member,wherein said cover member comprises a first fold anchored to saidsupport structure, and wherein said cover member comprises a second foldconnected to said first fold along a folded edge engaged by a drivingmember, wherein said driving member is formed by one or both of saidbody support member and said carriage, wherein said folded edge ismoveable in said first and second directions as said carriage is movedin said first and second direction respectively.
 9. The seatingstructure of claim 8 wherein said first fold comprises at least onetether.
 10. A seating structure comprising: a support structure; acarriage moveably supported by said support structure, wherein saidcarriage is moveable relative to said support structure in oppositefirst and second longitudinal directions; and a flexible body supportmember having a first portion coupled to said support structure, asecond portion coupled to said carriage, and a third curved portionpositioned between said first and second portions, wherein said thirdportion is moveable toward and away from said support structure as saidcarriage is moved relative to said support structure in said first andsecond directions respectively, wherein said body support member has aplurality of longitudinally extending slots defining a plurality oflongitudinally extending strips, wherein at least one of said pluralityof slots has a different length than at least one other of saidplurality of slots, and wherein said carriage comprises a leading edgedisposed adjacent said plurality of strips, wherein said leading edgecomprises a plurality of steps formed laterally across said leadingedge, with at least some of said plurality of steps corresponding to andaligned with at least some of said plurality of strips.
 11. A method ofadjusting the depth of a seat comprising: providing a support structure;a carriage moveably supported by said support structure; and a flexiblebody support member having a first portion coupled relative to saidsupport structure, a second portion coupled to said carriage, and athird curved portion positioned between said first and second portions;providing a cover member disposed over an outer surface of said bodysupport member and covering said third portion of said body supportmember; wherein said cover member comprises a first fold fixedly coupledrelative to said support structure and a second fold connected to saidfirst fold along a folded edge engaged by a driving member, wherein saiddriving member is formed by one or both of said body support member andsaid carriage; moving said carriage relative to said support structurein opposite first and second longitudinal directions; moving said thirdportion with said carriage toward and away from said support structureas said carriage is moved relative to said support structure in saidfirst and second directions respectively; and moving said folded edge insaid first and second longitudinal directions as said carriage is movedin said first and second direction respectively.
 12. The method of claim11 wherein said body support member comprises a first body supportmember and wherein said support structure is coupled to a second bodysupport member, said first and second body support members defining atleast in part a seat, wherein said first portion of said first bodysupport member is coupled to said second body support member.
 13. Themethod of claim 11 wherein said first fold comprises at least onetether.
 14. The method of claim 11 wherein said moving said carriagecomprises translating said carriage relative to said support structure.15. The method of claim 14 wherein said carriage is translatably coupledto said support structure with at least one slide member.